Plant or transplant a rose with bananas. Dig a hole that is larger than the root ball. For new roses, this is generally about 2 feet deep and 2 feet wide. For transplanted roses, it might be larger; it will depend upon the size of the root ball. Place a least one whole banana in the hole, then plant the rose as you normally would.
Bury an old banana next to the rose. Dig down about 4 inches; the depth is not for the rose, as much as it is about trying to bury the fruit deep enough to discourage banana-loving critters--like dogs, chipmunks or squirrels--from digging up your rose. You can stick the whole banana in the hole or break it up into pieces and bury it around the rose. You can also plant just the banana peels this way.
Bake the banana peels to accelerate the decomposition. Place the peels on a baking pan in a 350-degree oven and bake them until they are crisp. Allow them to cool and break them into pieces. Dig around the rose and plant the baked pieces.
Accelerate the banana's decomposition by making banana mash. Stick old bananas in the freezer. Once frozen, remove the brown tip from the banana and cut into pieces--peel and all--into a blender. Blend the banana until it makes a mash. Dig around the rose and spoon the mash into the hole.
Make a banana-puree tonic for the rose. Freeze old bananas. Remove the brown tip from the frozen banana and cut it up into a blender. Place enough water in the blender to cover the banana. Blend on the "liquefy" setting. Pour this puree into a gallon container (like an old milk container); you might have to use a funnel if the container has a small mouth, like a milk jug. Finish filling the gallon container with water, put the lid on it and shake it to mix. Pour the puree tonic on the base of the rose and on the surrounding soil. Use one banana for each gallon of tonic and use 1 gallon of tonic on each rose.
Make banana-peel liqueur. Cut up the peels of a banana into a spray bottle and cover the peels with warm water. Put the lid back on the bottle and leave for 2 weeks. The peels will ferment. Spray the rose bushes with this liquid.